ModbusTCP Control of ATV71 Drive

[Mark_Yedinak]

I have also recently encountered this error and believe there is a bug in the Modbus library. I have received a copy of the code which is not password protected and found an area in the code that is using a feedback node to store the Transaction ID. I believe this gets out of sync in the library when an error occurs. In my case, once I get into this state there is no recovery. I have limited access to the device I am communicating with because it is in a production environment (I am developing a replacement for a current application in use) and need to wait for maintenance windows to test. I will be looking into this further over the next week or so.I will update this thread as I find out more information.

[kjon]

Mark,

It looks like I may have had my Modbus Libraries mixed up. I was originally using the open free library and not the one that ships with the DSC module. I have since tried both the DSC version, the free version, and the Plasmionique version and they all seem to have issues. To recap: The DSC module version returns an Error 66 after 3 calls to the drive, the free version returns Error 538193 Transaction ID error, and the Plasmionique library won't even allow a single call to the drive and returns an Exception code 2, not sure why when all the other libraries are able to connect just fine. I'll keep an eye on that thread and hopefully we can figure out what is causing the error.

Thanks!

[Mark_Yedinak]

Try downloading the latest Modbus library from VIPM and see if that resolves your issue. I found the latest version corrected my problem with error 538193. It is version 1.2.1.42.

[kjon]

The funny thing is that the 538193 error I'm getting is happening as a result of using the VIPM modbus library! 

[Mark_Yedinak]

What fixed mine was not actually the latest from VIPM but the latest source code for the library. THat did fix my issue. All I did with the latest from source code control was to rebuild it with the password protection off so I could debug the library. After install that version I no longer got the error. According to the build spec the next build version would have been 1.2.1.43. I will contact the NI folks I worked with and see if we can get an updated version posted.

Interesting note about the library I got was that that the only change made was to change the transaction ID from a U8 to a U16. What I discovered is that I always encountered the error after the transaction ID rolled over.

[StevenD]

I am having the same problem. Using NI Modbus Library 1.2.1.42 and I get error 538193 after a few seconds. Any update on a new version or a fix to the current version?

[StevenD]

I had the wrong version installed. Upgrading to 1.2.1.42 seems to have fixed my problem. Sorry for any confusion.